Leading academics in Iran have written to the country’s president, Hassan Rouhani, to demand answers after a renowned environmentalist allegedly killed himself in prison.

The family of Kavous Seyed Emami, 63, a professor at Imam Sadegh University and founder of the Persian Wildlife Heritage Foundation, was told on Saturday that he had killed himself in prison two weeks after his arrest.

People take to the streets again despite heavy police presence and efforts to block social media apps

Iranian authorities have threatened a crackdown against protesters and scrambled to block social media apps allegedly used to incite unrest as the biggest demonstrations in nearly a decade continued for a fourth day.

People across Iran took to the streets again on Sunday evening in defiance of a heavy presence of riot police and state warnings to stay away.